1. Field of the Invention
The present invention concerns a rotary cutting head using cutting blades. It is advantageously intended for equipping portable cutting devices such as grass cutters, edge cutters, brush cutters, motorized, mowers, hedge trimmers and the like.
The invention also concerns portable cutting devices fit for being equipped with the cutting head disclosed in the following description.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 198
Portable motorized devices equipped with such cutting heads are currently used by professionals as well as by private persons, for example, for brush clearing, grass or lawn mowing.
These cutting heads are mounted to the distal end of a handle equipped with a U-shaped or dual handle for guiding and controlling the motor for the rotary drive of said cutting heads, the devices making use thereof may be equipped with a ring for attaching a carrying harness.
A cutting head of this kind uses a cutting blade made of metal or a composite material, and which may have various shapes: with three branches or lobes, circular (toothed disc or circular saw), or any other shape. Most often, these cutting blades are attached in a removable manner at the end of a handle, but this manner of fastening requires, on the one hand, knowledge of the specific principal of ‘left hand thread’ assembly and the use of special tools or not.
Document EP-1815732 describes a cutting head of a lawnmower featuring a rotary blade-supporting housing constituted by the assembly of an upper and a lower shell, this cutting head comprising a number of cutting blades that are independent of each other (four cutting blades according to the example shown), mounted on equidistant pivots borne by the lower shell. These vertical pivots are each positioned at equal radial distance from the axis of the shaft providing the rotary drive of the housing and they extend upward, parallel to said drive shaft. The positioning of the blades relative to their respective pivots is obtained by means of the upper shell locking itself on a central hub of the lower shell through the intermediary of a bayonet attachment.
The cutting head described in document EP 1815732 utilizes a number of narrow cutting blades with poor resistance to shocks caused by hard objects; the successive placement of each of these blades and to a certain extent, their removal, are difficult and necessarily long operations.
These inconveniences are encountered in the cutting head of the lawnmower described in document U.S. Pat. No. 3,320,733 which features two cutting blades that are independent of each other and mounted, diametrically opposed, on equidistant pivots borne by a disk driven in rotation by an axial drive shaft, these vertical pivots being placed, each, at equal radial distance from the drive shaft.